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We study hitting times in simple random walks on graphs, which measure the time required to reach specific target vertices. Our main result establishes a sharp lower bound for the variance of hitting times. For a simple random walk on a…

Probability · Mathematics 2024-03-25 Rafael Chiclana , Yuval Peres

Guo and Royle recently classified the connected cubic graphs without eigenvalues of their adjacency matrix in the open interval $(-1, 1)$, and raised the question of extending their classification to graphs of maximum degree at most $3$.…

Combinatorics · Mathematics 2026-05-01 Shenwei Huang , Zilin Jiang

Coalescing random walks is a fundamental stochastic process, where a set of particles perform independent discrete-time random walks on an undirected graph. Whenever two or more particles meet at a given node, they merge and continue as a…

Discrete Mathematics · Computer Science 2018-11-05 Varun Kanade , Frederik Mallmann-Trenn , Thomas Sauerwald

In this paper we study the spectrum of the random geometric graph $G(n,r)$, in a regime where the graph is dense and highly connected. In the \erdren $G(n,p)$ random graph it is well known that upon connectivity the spectrum of the…

Probability · Mathematics 2020-04-13 Kartick Adhikari , Robert J. Adler , Omer Bobrowski , Ron Rosenthal

Let $d,n\in \mathbb{N}$ be such that $d=\omega(1)$, and $d\le n^{1-a}$ for some constant $a>0$. Consider a $d$-regular graph $G=(V, E)$ and the random graph process that starts with the empty graph $G(0)$ and at each step $G(i)$ is obtained…

Combinatorics · Mathematics 2024-09-25 Sahar Diskin , Anna Geisler

Given a finite graph G, a vertex of the lamplighter graph consists of a zero-one labeling of the vertices of G, and a marked vertex of G. For transitive graphs G, we show that, up to constants, the relaxation time for simple random walk in…

Probability · Mathematics 2007-05-23 Yuval Peres , David Revelle

In this paper we determine the unique graph with minimum distance spectral radius among all connected graphs of fixed order and given edge connectivity.

Combinatorics · Mathematics 2014-09-19 Xiao-Xin Li , Yi-Zheng Fan , Yi Wang

We study the average probability that a discrete-time quantum walk finds a marked vertex on a graph. We first show that, for a regular graph, the spectrum of the transition matrix is determined by the weighted adjacency matrix of an…

Combinatorics · Mathematics 2021-08-24 Hanmeng Zhan

We derive an exact closed-form analytical expression for the distribution of the cover time for a random walk over an arbitrary graph. In special case, we derive simplified exact expressions for the distributions of cover time for a…

Mathematical Physics · Physics 2009-10-20 Nikola Zlatanov , Ljupco Kocarev

In the past decades, many scholars concerned which edge-extremal problems have spectral analogues? Recently, Wang, Kang and Xue showed an interesting result on $F$-free graphs [J. Combin. Theory Ser. B 159 (2023) 20--41]. In this paper, we…

Combinatorics · Mathematics 2025-03-14 Zhenzhen Lou , Changxiang He

Motivated by an old question of Gallai (1966) on the intersection of longest paths in a graph and the well-known conjectures of Lov\'{a}sz (1969) and Thomassen (1978) on the maximum length of paths and cycles in vertex-transitive graphs, we…

Combinatorics · Mathematics 2025-08-05 Sergey Norin , Raphael Steiner , Stephan Thomassé , Paul Wollan

Gao and Richter (1994) showed that every $3$-connected graph which embeds on the plane or the projective plane has a spanning closed walk meeting each vertex at most $2$ times. Brunet, Ellingham, Gao, Metzlar, and Richter (1995) extended…

Combinatorics · Mathematics 2017-12-19 Morteza Hasanvand

Distance-regular graphs are a key concept in Algebraic Combinatorics and have given rise to several generalizations, such as association schemes. Motivated by spectral and other algebraic characterizations of distance-regular graphs, we…

Combinatorics · Mathematics 2012-02-16 Cristina Dalfó , Edwin R. van Dam , Miquel Angel Fiol , Ernest Garriga , Bram L. Gorissen

A survey is presented of known results concerning simple random walk on the class of distance-regular graphs. One of the highlights is that electric resistance and hitting times between points can be explicitly calculated and given strong…

Probability · Mathematics 2013-01-29 Greg Markowsky

In this paper, we study how the distance spectral radius behaves when the graph is perturbed by grafting edges. As applications, we also determine the graph with $k$ cut vertices (respectively, $k$ cut edges) with the minimal distance…

Spectral Theory · Mathematics 2010-11-10 Xiaoling Zhang , Chris Godsil

A graph is trivial if it contains one vertex and no edges. The essential connectivity $\kappa^{\prime}$ of $G$ is defined to be the minimum number of vertices of $G$ whose removal produces a disconnected graph with at least two non-trivial…

Combinatorics · Mathematics 2024-06-26 Wenxiu Ding , Dan Li , Yu Wang , Jixiang Meng

Hakimi and Schmeichel determined a sharp lower bound for the number of cycles of length 4 in a maximal planar graph with $n$ vertices, $n\geq 5$. It has been shown that the bound is sharp for $n = 5,12$ and $n\geq 14$ vertices. However, the…

Combinatorics · Mathematics 2023-06-08 Ervin Győri , Addisu Paulos , Oscar Zamora

The spectral radius $\rho(G)$ of a graph $G$ is the largest eigenvalue of its adjacency matrix. Woo and Neumaier discovered that a connected graph $G$ with $\rho(G)\leq 3/2{\sqrt{2}}$ is either a dagger, an open quipu, or a closed quipu.…

Combinatorics · Mathematics 2011-12-22 Jingfen Lan , Linyuan Lu

Recently, random walks on dynamic graphs have been studied because of their adaptivity to the time-varying structure of real-world networks. In general, there is a tremendous gap between static and dynamic graph settings for the lazy simple…

Discrete Mathematics · Computer Science 2022-01-19 Nobutaka Shimizu , Takeharu Shiraga

We pose a new and intriguing question motivated by distributed computing regarding random walks on graphs: How long does it take for several independent random walks, starting from the same vertex, to cover an entire graph? We study the…

Probability · Mathematics 2007-11-20 Noga Alon , Chen Avin , Michal Koucky , Gady Kozma , Zvi Lotker , Mark R. Tuttle